Molecular mechanism of transcriptional regulation by insulin

我们制备了含有L型丙酮酸激酶（LPK）基因5 '侧翼区的转基因小鼠，该基因从核苷酸-189 50 +37开始，包括作为功能元件的增强子单元和TATA盒，连接到氯霉素乙酰转移酶（CAT）基因。转基因的表达被食物中的葡萄糖和果糖所刺激。将融合基因转染到培养的肝细胞中，并将细胞与胰岛素或不与胰岛素一起孵育。胰岛素刺激的CAT基因的表达在葡萄糖的存在下，但不是在丙酮酸的存在下。因此，我们认为LPK基因的增强子单位是胰岛素反应单位。HNF 1与L-III结合，L-III构成LPK基因的增强子单位。HNF 1的表达不受日粮控制.用CAT分析，我们发现葡萄糖激酶的5 '-侧翼区直到-1100含有对胰岛素应答的DNA区域。

We produced transgenic mice containing the 5'-flanking region of the L-type pyruvate kinase (LPK) gene from nucleotide -189 50 +37, which includes an enhancer unit and TATA box as functional elements, linked to the chloramphenicol acetyltransferase (CAT) gene. Transgene expression was stimulated by both dietary glucose and fructose in the liber. The fusion gene was also transfected into cultured hepatocytes and the cells were incubated with or without insulin. Insulin stimulated expression of the CAT gene in the presence of glucose, but not in the presence of pyruvate. Thus, we suggest that an enhancer unit of the LPK gene is insulin response unit.2. HNF1 binds to L-III, which constitutes an enhancer unit of the LPK gene. Expression of HNF1 was not under dietary control.3. Using CAT assay, we showed that the 5'-flanking region of the glucokinase up to -1100 contained the DNA region responsive to insulin.